diff --git a/screen_ui.h b/screen_ui.h
index fd9f471..e961c1c 100644
--- a/screen_ui.h
+++ b/screen_ui.h
@@ -72,6 +72,11 @@
     void SetColor(UIElement e);
 
   protected:
+    // The margin that we don't want to use for showing texts (e.g. round screen, or screen with
+    // rounded corners).
+    const int kMarginWidth;
+    const int kMarginHeight;
+
     // The scale factor from dp to pixels. 1.0 for mdpi, 4.0 for xxxhdpi.
     const float density_;
 
@@ -138,11 +143,6 @@
     int char_width_;
     int char_height_;
 
-    // The margin that we don't want to use for showing texts (e.g. round screen, or screen with
-    // rounded corners).
-    int margin_width_;
-    int margin_height_;
-
     pthread_mutex_t updateMutex;
 
     virtual bool InitTextParams();